Discontinuous reception alignment in dual connectivity networks

ABSTRACT

A 3GPP LTE protocol enhancement realizes the full benefit of discontinuous reception (DRX) in Long Term Evolution networks by coordinating and aligning DRX operations for conserving power and timing overhead. A dual connectivity enabled User Equipment (UE) comprising a processor and transceiver is configured to align DRX configuration between counterpart Evolved Node Bs (eNB)s, wherein counterpart eNBs are a Master eNB (MeNB) and a Secondary eNB (SeNB) simultaneously connected to the UE, communicate system frame timing and system frame number (SFN) information between the counterpart eNBs, align DRX start offset (drxStartOffset) values for the counterpart eNBs according to the communicated system frame timing and SFN information to compensate for offsets in system frame timing, and allow the start of a DRX ON duration at specific frame or sub-frame times determined by the drxStartOffset values, after the expiration of a DRX inactivity timer.

PRIORITY CLAIM

The present Application for Patent claims the benefit of priority under35 U.S.C. 119(e) to U.S. Provisional Patent Application Ser. No.61/933,862, entitled “UE ASSISTED TIME SYNCHRONIZATION BETWEEN SENB ANDMENB DUE TO SFN OFFSET TO ACHIEVE DRX ALIGNMENT IN LTE DUAL CONNECTIVITYARCHITECTURE,” filed Jan. 30, 2014, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

Examples generally relate to Long Term Evolution (LTE) networks. One ormore examples relate to the implementation of Discontinuous Reception(DRX) alignment in LTE dual connectivity network architecture(s).

BACKGROUND

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and other media.These systems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE)systems, and orthogonal frequency division multiple access (OFDMA)systems.

Dual connectivity is a new innovative network architecture that allows aUser Equipment (UE) to connect with more than one base station and/ornetwork cell simultaneously. The UE can connect with a Master Cell Group(MCG) and as Secondary Cell Group (SCG) at the same time by connectingto a Master Evolved Node B (MeNB) and a Secondary Evolved Node B (SeNB)at the MCG and SCG respectively. The simultaneously connected MeNB andthe SeNB are counterparts in DRX operations. Because the MeNB and SeNBhave separate and independent DRX operations for Dual Connectivityenabled UEs, the UE may remain active (i.e., wasting power and signalingresources) longer than necessary if these DRX operations are notaligned. Thus, in order to realize the full benefit of proposed dualconnectivity networks, there is now a need for enhancements in current3GPP LTE standards to coordinate and align DRX operations.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 shows a high level block diagram illustrating an example of dualconnectivity in a cellular network, according to some embodiments;

FIG. 2 illustrates the effect of unaligned DRX at a UE, according tosome embodiments;

FIG. 3 illustrates DRX alignment at a UE, according to some embodiments;

FIG. 4 illustrates a Medium Access Control (MAC) Element for DRXalignment between a MeNB and a SeNB, according to some embodiments;

FIG. 5 is a high level overview flowchart of DRX Alignment in DualConnectivity Networks, according to some embodiments;

FIG. 6 shows a functional diagram of an exemplary communication stationin accordance with some embodiments; and

FIG. 7 shows a block diagram of an example of a machine upon which, anyof one or more techniques (e.g., methods) discussed herein may beperformed.

DESCRIPTION OF EMBODIMENTS

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

The terms “communication station”, “station”, “handheld device”, “mobiledevice”, “wireless device” and “User Equipment” (UE) as used hereinrefer to a wireless communication device such as a cellular telephone,smartphone, tablet, netbook, wireless terminal, laptop computer,femtocell, High Data Rate (HDR) subscriber station, access point, accessterminal, or other personal communication system (PCS) device. Thedevice may be either mobile or stationary.

The term “access point” as used herein may be a fixed station. An accesspoint may also be referred to as an access node, a base station or someother similar terminology known in the art. An access terminal may alsobe called a mobile station, a User Equipment (UE), a wirelesscommunication device or some other similar terminology known in the art.Dual Connectivity in wireless cellular networks has been approved bystandards bodies for 3rd Generation Partnership Project (3GPP) LTEadvanced releases. Dual connectivity allows a UE to simultaneouslyconnect with more than one cell or eNB. A UE may simultaneously connectto a MeNB and a SeNB.

The 3GPPP standards body has agreed that the MeNB and SeNB supportseparate and independent DRX operations for a Dual Connectivity UE.However, independent DRX operations may result in the UE over consumingresources such as the UE's battery power by causing the UE tounnecessarily maintain an active state when dual DRX operations are notaligned.

Dual connectivity MeNBs and SeNBs are not co-located. Therefore, theirSystem Frame Numbers (SFNs) (i.e., system frame timings) are notsynchronized or aligned. As a result, even if a MeNB and a SeNB haveidentical DRX configuration parameters, alignment (i.e., a simultaneousstart of their DRX ON Durations) is not guaranteed. Unfortunately,current 3GPP LTE specifications do not provide signaling and protocolsupport for power saving DRX alignment or eNB coordination of DRXconfigurations.

A method and apparatus for DRX alignment are disclosed in FIGS. 1-7.Coordinated DRX start offsets (drxStartOffsets) are determined tocompensate for the offset between SFNs of the SeNB and the MeNB. Amechanism for informing the counterpart MeNB and the SeNB of eachother's system frame timings at least at the sub-frame level ofgranularity, or SFNs, is provided for determining the offset, as well asbefitting other LTE dual connectivity operations. DRX configurationparameters are negotiated between the counterpart MeNB and the SeNB overtheir X2 interfaces to align the DRX configuration. For example, theMeNB and the SeNB may select equal DRX ON Durations and equal (orinteger multiple) DRX Long cycles. The start of DRX ON Duration isdetermined by the drxStartOffset, which allows the start of DRX Onduration only at specific frames and/or sub-frames after expiration of aDRX inactivity timer.

FIG. 1 shows a high level block diagram illustrating an example of dualconnectivity in a cellular network 100. Cell 102 a, belonging to a MCG,comprises MeNB 104. Cell 102 b, belonging to a SCG, comprises SeNB 106.UE 108 is simultaneously connected to MeNB 104 and SeNB 106. MeNB 104and SeNB 106 may communicate via an X2 interface protocol.

FIG. 2 illustrates the effect of unaligned DRX at a UE 200. Independentand unaligned DRX operations performed by MeNB 104 and SeNB 106 mayincrease the UE's 108 overall active state durations and concomitant UE108 power consumption. As shown, UE 108 supports operational states forDRX communications from a MeNB 202 and a SeNB 204, resulting in overallcombined DRX communication states 206.

Active state periods of the UE 108 operation are determined by theexpiration of an inactivity timer, the value of DRX cycle and the valueof a DRX start offset value “drxStartOffset”. The inactivity timerexpires after a predetermined amount of time since the last packetactivity from the same eNB (i.e., the MeNB 104 and the SeNB 106 each hasits own independent packet activity timer). The UE's 108 DRX logiccontinues to consume signaling and power resources as long as theinactivity timer has not expired. The UE 108 operates in an active statehaving duration 212 a, starting at time T1 and ending at time T3, withrespect to the MeNB 104. The UE 108 simultaneously operates in an activestate, also having duration 212 a, starting at time T2 and ending attime T4, with respect to the SeNB 106.

Following the end of each active state period 212, the UE 108 alternatesbetween ON states 214 where the UE 108 wakes up and looks for packetactivity, and a DRX sleep state 216 where the UE 108 sleeps to conservethe UE's 108 battery power. Because the DRX active states from the MeNB202 and the SeNB 204 are unaligned, the combined active state period forboth MeNB 104 and SeNB 106 signals (202 and 204 respectively) has alonger duration 212 b, than either of the uncombined active state perioddurations 212 a. The combined ON state period 218 also has a longerduration than either of the uncombined ON state period durations 214.The extended operation of the UE 108 in the combined active state 212 band ON 218 state periods generates wasteful power consumption by the UE108.

To help prevent unnecessary power consumption by the UE 108, values ofdrxStartOffset 208 for the MeNB 104 and/or the SeNB 106 need to bealigned to compensate for inherent SFN offsets of the MeNB 104 and theSeNB 106. Without adjusting the drxStartOffsets 208, DRX alignment maynot be able to be achieved even when the MeNB 104 and SeNB 106 DRX wereidentically configured.

FIG. 3 illustrates Dual Connection DRX alignment 300 at a UE. The UE 108supports operational states for DRX communications from a MeNB 302 and aSeNB 304, resulting in overall combined DRX communication states 306.

DRX alignment decreases a UE's 108 overall active state 312 and ON state314 durations as shown in FIG. 3. To maximize user power savings duringDRX operations in Dual Connection network architectures where a UE 108may have separate and independent DRX operations for a MeNB 104 and aSeNB 106, the total combined active state 316 and ON state 314 statedurations of the UE 108 may be minimized. The total combined activestate 316 and ON 314 state durations are minimized when UE 108 DRX ONstate durations 314 are aligned with respect to the MeNB 104 and theSeNB 106.

MeNB 104 and SeNB 106 DRX activity state 312 and ON 314 state durationsare aligned to time T1 using correctly calculated drxStartOffsets. Thecorrect drxStartOffsets ensure that all following combined ON statedurations 314 occur simultaneously in time 306. The combined activityand ON states 306 cannot overlap or have the extended durations seen inFIG. 2.

To align the DRX ON state durations 314, drxStartOffsets for the MeNB104 and the SeNB 106 are calculated to compensate for SFN timing offsetsbetween the SeNB 106 and the MeNB 104. However, for calculating thedrxStartOffsets, the MeNB 104 and the SeNB 106 should have knowledge ofeach other's SFN timings.

A dual connected UE 108 is aware of system frame timings and SFNs ofboth connected eNBs (i.e., the MeNB 104 and the SeNB 106). In one UE 108assisted embodiment, an eNB (104 or 106) can instruct the UE 108 totransmit the system frame timing and SFN information of its counterpartdual connected eNB (104 or 106) for calculating drxStartOffsets. Inanother UE 108 unassisted embodiment, signaling messages having systemframe timing and SFN information are exchanged over an X2 interfacedirectly between the MeNB 104 and the SeNB 106 for calculatingdrxStartOffsets. FIG. 4 details novel MAC Control Element (CE) datastructures for UE 108 assisted alignment. FIG. 5 details a messagingmechanism for acquiring system frame timing and SFN information of acounterpart eNB in Dual Connectivity over the X2 interface.

FIG. 4 illustrates MAC Control Element components 400 for UE 108assisted DRX alignment between a MeNB 104 and a SeNB 106. The MeNB 104and/or SeNB 106 should have knowledge of the system frame timing and SFNof its counterpart eNB to align the DRX operations for a Dual Connectioncapable UE 108. LTE network architectures comprise a SFN, between 0 and1023, that is updated every 10 milliseconds (ms), and a sub-frame number(SF) between 0 and 9 that is updated every 1 ms.

In a UE 108 assisted embodiment, a SFN used to calculate adrxStartOffset value for starting DRX operations is broadcast to a UE108 by an eNB in a Master Information Block (MIB) message, which the UE108 can forward to the counterpart eNB. Because a dual connected UE 108is synchronized to, and aware of, the system frame timing and SFN ofboth of the MeNB 104 and SeNB 106, the MeNB 104 (or the SeNB 106) canask the UE 108 to send the system frame timing and SFN information ofits counterpart eNB over the air interface for the purpose of DRXalignment as well as other dual connectivity needs. Either the MeNB 104or the SeNB 106 can initiate this approach to obtain the system frametiming and SFN information of the other eNB.

For example, the MeNB 104 can transmit a novel downlink (DL) MAC ControlElement (CE) to a dual connectivity UE 108 for requesting the systemframe timing and SFN information of its counterpart SeNB 106. The UE 108may reply by returning a novel Uplink (UL) MAC CE containing therequested system frame timing and SFN information. Novel CE datastructures for exchanging system frame timing and SFN information ofcounterpart eNBs via UL and DL are detailed below.

In various embodiments, novel Radio Resource Control (RRC) messages, ora novel Information Element (IE) included in the existing RRC messagestructure, are defined to enable the UE 108 assisted embodiments toacquire system frame timing and SFN information of a counterpart eNB inDual Connectivity network architectures. In one embodiment, a novel DLMAC CE is used by an eNB to request a Dual Connectivity enabled UE 108to transmit system frame timing and SFN information of its counterparteNB. The DL MAC CE comprises a DL MAC CE sub-header 402 having a LogicalChannel Identifier (LCID) 408 selected from the reserved LCID pool forDownlink Shared Channel (DL-SCH) used to identify the DL MAC CE forrequesting counterpart system frame information. The DL MAC CE header102 has no (or zero byte) data field.

Likewise, a novel UL MAC CE is used by a Dual Connectivity enabled UE108 to respond to the request for counterpart eNB system frame timingand SFN information. The UL MAC CE comprises a UL MAC CE sub-header 404having a Logical Channel Identifier (LCID) 410 selected from thereserved LCID pool for UL Shared Channel (UL-SCH) used to identify theUL MAC CE for responding to requests for counterpart system frameinformation and a MAC CE data field 406.

The MAC CE data field 406 carries the system frame timing information412 of the counterpart eNB. The system frame timing information 412comprises a SFN value 414, as well as sub-frame number value 416 of thecounterpart eNB.

In other direct embodiments, messages having system frame timing and SFNinformation are exchanged over an X2 interface directly between the MeNB104 and the SeNB 106 for calculating drxStartOffsets. Either eNB may askits counterpart eNB to reply with system frame timing and SFNinformation. In reply, the counterpart eNB responds with system frametiming and SFN information with the absolute system time stamp. Anabsolute system time stamp compensates for non-ideal backhaul delays ofup to several ms.

In dual connectivity, RRC messages carrying DRX configuration IEs forthe MeNB 104 and the SeNB 106 are transmitted by the MeNB 104. The SeNB106 sends its DRX configuration IE to its counterpart MeNB 104 over theX2 interface, such that it can be forwarded to the UE 108. A new systemtiming IE may be added to the existing SeNB 106 DRX configuration IEcomprising system frame timing and SFN information stamped with absolutesystem time. This system timing IE is not forwarded to the UE 108 by theMeNB 104 because it is primarily used by the MeNB 104 to adjust the MeNB104 drxStartOffset in order to align its DRX Configuration with that ofthe SeNB 106 and to ensure correct alignment of DRX operations of dualconnectivity UEs 108.

FIG. 5 is a high level overview flowchart of DRX Alignment in DualConnectivity Networks 500. Beginning in operation 502, system timinginformation is exchanged between the MeNB 104 and the SeNB 106. DRXconfiguration parameters are negotiated between the MeNB 104 and theSeNB 106, either over their X2 interfaces or relayed by the UE 108, foraligning the DRX configuration. System frame timing and SFN informationis communicated between the counterpart eNBs. The information may berequested by either the MeNB 104 or the SeNB 106 and relayed through theUE 108 by the counterpart eNB, or either eNB may request the informationdirectly from its counterpart eNB via their X2 interface.

Thus, system frame timing and SFN information is communicated betweencounterpart eNBs, wherein the counterpart eNBs are a MeNB and aSecondary SeNB simultaneously connected to the UE. Control proceeds tooperation 504

In operation 504, DRX timing is aligned. DRX start offset(drxStartOffset) values for the counterpart eNBs are aligned accordingto the communicated system frame timing and SFN information in order tocompensate for offsets in the system frame timing. The start of DRX ONDuration periods is determined by the drxStartOffset value. For example,the MeNB 104 and the SeNB 106 may select equal DRX ON durations andequal (or integer multiple) DRX Long cycles. Control proceeds tooperation 506.

After DRX configuration and alignment, the start of DRX On durations areallowed at specific frame and/or sub-frame times, after expiration of aDRX inactivity timer in operation 506.

FIG. 6 shows a functional diagram of an exemplary communication station600 in accordance with some embodiments. In one embodiment, FIG. 6illustrates a functional block diagram of a communication station thatmay be suitable for use as a MeNB 104 (FIG. 1) or SeNB 106 (FIG. 1) inaccordance with some embodiments. The communication station 600 may alsobe suitable for use as a handheld device, mobile device, cellulartelephone, smartphone, tablet, netbook, wireless terminal, laptopcomputer, femtocell, HDR subscriber station, access point, accessterminal, or other PCS device.

The communication station 600 may include physical layer circuitry 602having a transceiver 610 for transmitting and receiving signals to andfrom other communication stations using one or more antennas 601. Thecommunication station 600 may also comprise MAC circuitry 604 forcontrolling access to the wireless medium. The communication station 600may also include processing circuitry 606 and memory 608 arranged toperform the operations described herein. In some embodiments, thephysical layer circuitry 602 and the processing circuitry 606 may beconfigured to perform operations detailed in FIG. 5.

In accordance with some embodiments, the MAC circuitry 604 may bearranged to contend for a wireless medium, and configure frames orpackets for communicating over the wireless medium and the physicallayer circuitry 602 may be arranged to transmit and receive signals. Thephysical layer circuitry 602 may include circuitry formodulation/demodulation, up-conversion/down-conversion, filtering,amplification, etc. In some embodiments, the processing circuitry 606 ofthe communication station 600 may include one or more processors. Insome embodiments, two or more antennas 601 may be coupled to thephysical layer circuitry 602 arranged for sending and receiving signals.The memory 608 may store information for configuring the processingcircuitry 606 to perform operations for configuring and transmittingmessage frames and performing the various operations described herein.The memory 608 may comprise any type of memory, including non-transitorymemory, for storing information in a form readable by a machine (e.g., acomputer). For example, the memory 608 may comprise a computer-readablestorage device, read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media.

In some embodiments, the communication station 600 may be part of aportable wireless communication device, such as a personal digitalassistant (PDA), a laptop or portable computer with wirelesscommunication capability, a web tablet, a wireless telephone, asmartphone, a wireless headset, a pager, an instant messaging device, adigital camera, an access point, a television, a medical device (e.g., aheart rate monitor, a blood pressure monitor, etc.), or another devicethat may receive and/or transmit information wirelessly.

In some embodiments, the communication station 600 may include one ormore antennas 601. The antennas 601 may comprise one or more directionalor omnidirectional antennas, including, for example, dipole antennas,monopole antennas, patch antennas, loop antennas, micro-strip antennas,or other types of antennas suitable for transmission of RF signals. Insome embodiments, instead of two or more antennas, a single antenna withmultiple apertures may be used. In these embodiments, each aperture maybe considered a separate antenna. In some multiple-input multiple-output(MIMO) embodiments, the antennas 601 may be effectively separated forspatial diversity and the different channel characteristics that mayresult between each of the antennas 601 and the antennas of atransmitting station.

In some embodiments, the communication station 600 may include one ormore of a keyboard, a display, a non-volatile memory port, multipleantennas, a graphics processor, an application processor, speakers, andother mobile device elements. The display may be a Liquid CrystalDisplay (LCD) screen including a touch screen.

Although the communication station 600 is illustrated as having severalseparate functional elements, two or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingdigital signal processors (DSPs), and/or other hardware elements. Forexample, some elements may comprise one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs), andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements of the communication station 600 may refer to one ormore processes operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory memory mechanism for storing information in a formreadable by a machine (e.g., a computer). For example, acomputer-readable storage device may include Read-Only-Memory (ROM),random-access memory (RAM), magnetic disk storage media, optical storagemedia, flash-memory devices, and other storage devices and media. Insome embodiments, the communication station 600 may include one or moreprocessors and may be configured with instructions stored on acomputer-readable storage device memory 608.

FIG. 7 illustrates a block diagram of an example of a machine 700 uponwhich any one or more of the techniques (e.g., methodologies) discussedherein may be performed. In one embodiment, the machine 700 may be a UE108. In alternative embodiments, the machine 700 may operate as astandalone device or may be connected (e.g., networked) to othermachines. In a networked deployment, the machine 700 may operate in thecapacity of a server machine, a client machine, or both in server-clientnetwork environments. In an example, the machine 700 may act as a peermachine in a peer-to-peer (P2P) (or other distributed) networkenvironment. The machine 700 may be a personal computer (PC), a tabletPC, a set-top box (STB), a personal digital assistant (PDA), a mobiletelephone, a web appliance, a network router, switch or bridge, or anymachine capable of executing instructions (sequential or otherwise) thatspecify actions to be taken by that machine, such as a base station.Further, while a single machine 700 is illustrated, the term “machine”shall also be taken to include any collection of machines thatindividually or jointly execute a set (or multiple sets) of instructionsto perform any one or more of the methodologies discussed herein, suchas cloud computing, software as a service (SaaS), or other computercluster configurations.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operationswhen operating. A module includes hardware. In an example, the hardwaremay be specifically configured to carry out a specific operation (e.g.,hardwired). In another example, the hardware may include configurableexecution units (e.g., transistors, circuits, etc.) and a computerreadable medium containing instructions, where the instructionsconfigure the execution units to carry out a specific operation when inoperation. The configuring may occur under the direction of theexecutions units or a loading mechanism. Accordingly, the executionunits are communicatively coupled to the computer readable medium whenthe device is operating. In this example, the execution units may be amember of more than one module. For example, under operation, theexecution units may be configured by a first set of instructions toimplement a first module at one point in time and reconfigured by asecond set of instructions to implement a second module at a secondpoint in time.

The machine (e.g., computer system) 700 may include a hardware processor702 (e.g., a central processing unit (CPU), a graphics processing unit(GPU), a hardware processor core, or any combination thereof), a mainmemory 704 and a static memory 706, some or all of which may communicatewith each other via an interlink (e.g., bus) 708. The machine 700 mayfurther include a power management device 732, a graphics display device710, an alphanumeric input device 712 (e.g., a keyboard), and a userinterface (UI) navigation device 714 (e.g., a mouse). In an example, thegraphics display device 710, alphanumeric input device 712, and UInavigation device 714 may be a touch screen display. The machine 700 mayadditionally include a storage device (i.e., drive unit) 716, a signalgeneration device 718 (e.g., a speaker), a network interfacedevice/transceiver 720 coupled to antenna(s) 730, and one or moresensors 728, such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The machine 700 may include an outputcontroller 734, such as a serial (e.g., universal serial bus (USB),parallel, or other wired or wireless (e.g., infrared (IR), near fieldcommunication (NFC), etc.) connection to communicate with or control oneor more peripheral devices (e.g., a printer, card reader, etc.)

The storage device 716 may include a machine readable medium 722 onwhich is stored one or more sets of data structures or instructions 724(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 724 may alsoreside, completely or at least partially, within the main memory 704,within the static memory 706, or within the hardware processor 702during execution thereof by the machine 700. In an example, one or anycombination of the hardware processor 702, the main memory 704, thestatic memory 706, or the storage device 716 may constitute machinereadable media.

While the machine readable medium 722 is illustrated as a single medium,the term “machine readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 724.

The term “machine readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine 700 and that cause the machine 700 to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding, or carrying data structures used by or associatedwith such instructions 724. Non-limiting machine readable medium 722examples may include solid-state memories, and optical and magneticmedia. In an example, a massed machine readable medium comprises amachine readable medium 722 with a plurality of particles having restingmass. Specific examples of massed machine readable media may include:non-volatile memory, such as semiconductor memory devices (e.g.,Electrically Programmable Read-Only-Memory (EPROM), or ElectricallyErasable Programmable Read-Only-Memory (EEPROM)) and flash memorydevices; magnetic disks, such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

The instructions 724 may further be transmitted or received over acommunications network 726 using a transmission medium via the networkinterface device/transceiver 720 utilizing any one of a number oftransfer protocols (e.g., frame relay, internet protocol (IP),transmission control protocol (TCP), user datagram protocol (UDP),hypertext transfer protocol (HTTP), etc.). Example communicationsnetworks 726 may include a local area network (LAN), a wide area network(WAN), a packet data network (e.g., the Internet), mobile telephonenetworks (e.g., cellular networks), Plain Old Telephone Service (POTS)networks, wireless data networks (e.g., Institute of Electrical andElectronics Engineers (IEEE) 802.11 family of standards known as Wi-Fi®,IEEE 802.16 family of standards known as WiMax®), IEEE 802.15.4 familyof standards, and peer-to-peer (P2P) networks, among others. In anexample, the network interface device/transceiver 720 may include one ormore physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one ormore antennas 730 to connect to the communications network 726. In anexample, the network interface device/transceiver 720 may include aplurality of antennas 730 to wirelessly communicate using at least oneof single-input multiple-output (SIMO), multiple-input multiple-output(MIMO), or multiple-input single-output (MISO) techniques. The term“transmission medium” shall be taken to include any intangible mediumthat is capable of storing, encoding or carrying instructions 724 forexecution by the machine 700, and includes digital or analogcommunications signals or other intangible media to facilitatecommunication of such software.

What is claimed is:
 1. A dual connectivity enabled User Equipment (UE)comprising a processor and transceiver configured to: communicate systemframe timing and system frame number (SFN) information betweencounterpart evolved Node Bs (eNBs), wherein the counterpart eNBs are aMaster eNB (MeNB) and a Secondary eNB (SeNB) simultaneously connected tothe UE; align Discontinuous Reception (DRX) start offset(drxStartOffset) values for the counterpart eNBs according to the systemframe timing and SFN information to compensate for offsets in the systemframe timing; start DRX ON durations at specific frame or sub-frametimes determined by the aligned drxStartOffset values; and use thealigned DRX start offset values for beginning active state periods whenan inactivity timer expires.
 2. The UE of claim 1 further configured toreceive Radio Resource Control messages carrying DRX configurationInformation Elements (IE)s from the counterpart eNBs for aligning DRXconfigurations, wherein the DRX configuration IEs comprise the systemframe timing and SFN information stamped with absolute system time. 3.The UE of claim 1 further configured to support a download (DL) MediumAccess Control (MAC) Control Element (CE) comprising a sub-header havinga Logical Channel Identifier (LCID) selected from a reserved LCID poolfor Downlink Shared Channel (DL-SCH) used to identify the DL MAC CE forcommunicating the system frame timing and SFN information.
 4. The UE ofclaim 1 further configured to support an uplink (UL) MAC CE comprising asub-header having a Logical Channel Identifier (LCID) selected from areserved LCID pool for UL Shared Channel (UL-SCH) used to identify theUL MAC CE for communicating the system frame timing and system framenumber information.
 5. The UE of claim 1 further configured to operateaccording to equal DRX ON durations and equal DRX Long cycles.
 6. The UEof claim 1 further configured to operate according to integer multipleDRX long cycles.
 7. The UE of claim 1 further configured to conservebattery power by using the aligned DRX start offset values to minimizedurations of an active state.
 8. The UE of claim 1 further configured toalign the drxStartOffset values so that the aligned values ensure thatMeNB and SeNB active state durations occur simultaneously.
 9. The UE ofclaim 1 further configured to receive instructions from a MeNB or a SeNBto transmit the system frame timing and SFN information of thecounterpart MeNB or SeNB for aligning the drxStartOffset values.
 10. Anon-transitory computer readable storage device including instructionsstored thereon, which when executed by one or more processor(s) of aUser Equipment (UE), cause the UE to perform operations to: aligndiscontinuous reception (DRX) configuration between counterpart EvolvedNode Bs (eNB)s, wherein the counterpart eNBs are a Master eNB (MeNB) anda Secondary eNB (SeNB) simultaneously connected to the UE; communicatesystem frame timing and system rame number (SFN) information between thecounterpart eNBs; align discontinuous reception start offset(drxStartOffset) values for the counterpart eNBs according to the systemframe timing and SFN information to compensate for offsets in systemframe timing; start DRX ON durations at specific frame or sub-frametimes determined by the aligned drxStartOffset values; and use thealigned drxStartOffset values for beginning active state periods, afterthe expiration of a DRX inactivity timer.
 11. The non-transitorycomputer readable storage device of claim 10 wherein the operationsfurther configure the UE to receive Radio Resource Control messagescarrying DRX configuration Information Elements (IE)s from thecounterpart eNBs for aligning DRX configurations, wherein the DRXconfiguration IEs comprise the system frame timing and SFN informationstamped with absolute system time.
 12. A method for aligningdiscontinuous reception (DRX) in a dual connectivity wireless networkcomprising; exchanging system frame timing and system frame number (SFN)information between a Master Evolved Node B (MeNB) and a SecondaryEvolved Node B (SeNB) simultaneously connected to a User Equipment (UE);and determining DRX start offset (drxStartOffset) values for the MeNBand the SeNB according to the exchanged system frame timing and SFNinformation, for initiating aligned packet activity with the UE atspecific frame and/or sub-frame times; wherein the aligned packetactivity is associated with DRX ON durations at specific frame orsub-frame times determined by aligned drxStartOffset values forbeginning active state periods when an inactivity timer expires.
 13. Themethod of claim 12 wherein the system frame timing and SFN informationis exchanged over an X2 interface or relayed by the UE.
 14. The methodof claim 12 wherein the system frame timing and SFN information isexchanged in a Medium Access Control (MAC) Control Element (CE)comprising data fields for carrying the system frame timing and SFNinformation.
 15. The method of claim 12 wherein the system frame timingand SFN information for determining the drxStartOffset vaules isidentified by a unique Logical Channel Identifier (LCID).
 16. The methodof claim 12 wherein the drxStartOffset values for initiating alignedpacket activity are determined by compensating for offsets in systemframe timing between the MeNB and the SeNB.
 17. The method of claim 12wherein a system timing Information Element (IE) is added to SeNBconfiguration parameters, the IE comprising the system frame timing andSFN information stamped with absolute system time.
 18. A dualconnectivity enabled User Equipment (UE) comprising: memory configuredto store system frame timing and system frame number (SFN) information;and processing circuitry configured to: communicate the system frametiming and SFN information between counterpart evolved Node Bs (eNBs),wherein the counterpart eNBs are a Master eNB (MeNB) and a Secondary eNB(SeNB) simultaneously connected to the UE; align Discontinuous Reception(DRX) start offset (drxStartOffset) values for the counterpart eNBsaccording to the system frame timing and SFN information to compensatefor offsets in the system frame timing; start DRX ON durations atspecific frame or sub-frame times determined by the aligneddrxStartOffset values; and use the aligned DRX start offset values forbeginning active state periods when an inactivity timer expires.
 19. TheUE of claim 18 further configured to receive Radio Resource Controlmessages carrying DRX configuration Information Elements (IE)s from thecounterpart eNBs for aligning DRX configurations, wherein the DRXconfiguration IEs comprise the system frame timing and SFN informationstamped with absolute system time.
 20. The UE of claim 18 furtherconfigured to support a download (DL) Medium Access Control (MAC)Control Element (CE) comprising a sub-header having a Logical ChannelIdentifier (LCID) selected from a reserved LCID pool for Downlink SharedChannel (DL-SCH) used to identify the DL MAC CE for communicating thesystem frame timing and SFN information.
 21. The UE of claim 18 furtherconfigured to support an uplink (a) MAC CE comprising a sub-headerhaving a Logical Channel Identifier (LCID) selected from a reserved LCIDpool for UL Shared Channel (UL-SCH) used to identify the UL MAC CE forcommunicating the system frame timing and system frame numberinformation.
 22. The UE of claim 18 further configured to operateaccording to equal DRX ON durations and equal DRX Long cycles.
 23. TheUE of claim 18 further configured to operate according to integermultiple DRX long cycles.